One area of automotive vehicle technology that is evolving rapidly is the area of autonomous or semi-autonomous drive capabilities. This is enabled through the introduction of sensors, for sensing road vehicle motion and surroundings, and actuators, for controlling different road vehicle functionalities, such as steering, throttling and braking. Increased on-board data processing capabilities ties together these sensors and actuators such that the autonomous or semi-autonomous drive capabilities are enabled.
When a road vehicle runs in autonomous mode, which means that a driver thereof is not required to perform maneuvers, the road vehicle usually is dependent on multiple data sources as inputs to perform the autonomous driving, such as detection of surrounding vehicles, traffic lanes, obstacles, data from navigation systems and so on.
In the case where an automated function takes responsibility for a particular driving task, the risk level must be kept low. For an autonomous road vehicle, this means that the autonomous drive system must be capable to plan and realize a safe vehicle trajectory for all possible situations.
In case the autonomous road vehicle cannot guarantee safe driving over a longer time horizon, it must hand over control to the driver or bring the road vehicle to a stop, i.e. perform a safe maneuver. This may be required if for instance a fault is detected on a vital system component.
Stopping a road vehicle in a lane or on a shoulder of a road may in some situations increase the risk of an accident, most notably the risk of rear-end collisions. Consequently, in order to eliminate this risk it is desirable that a driver of the road vehicle is capable of taking over the driving task if the road vehicle needs to perform a safe maneuver. The road vehicle may in such cases be arranged to request the driver to take over by e.g. visual or audible communication.
A previous attempt at addressing these issues is provided by US 2011 241 862 A1, that relates to a method and system for ensuring operation of limited-ability autonomous driving vehicles that includes monitoring a plurality of specific conditions necessary for preferred and reliable use of limited-ability autonomous driving, and initiating a fault handling and degradation strategy configured to maneuver the vehicle to a preferred state if the driver is unable to manually control the vehicle when at least one of the specific conditions is either violated or will become violated. The vehicle can be maneuvered to—and stopped on the side of the road e.g. in response to determination of an “Inattentive Driver” or a critical failure.
The system according to US 2011 241 862 A1 may provide a warning as it attempts to re-gain the operator's attention to manually take control of the vehicle. The system may adjust warning options based on driver response or lack of response, and escalate or stop warnings. For instance, chimes may ring through an entertainment system of the vehicle, a voice may attempt to alert the operator, the operator's seat may vibrate, lights may flash on the instrument panel, or some other appropriate means may be used to re-gain the operator's attention.
The vehicle according to US 2011 241 862 A1 will in some instances be required to maneuver as soon as possible to the side of the road (e.g., shoulder), turn on the hazard lights, slow to a stop, and apply the parking brake. The vehicle may also be required to turn the hazard lights on, honk the horn, pop the hood after stopping, and request roadside assistance through a system such as OnStar. Furthermore, a driver monitoring system that includes monitoring the attentiveness of a driver may be included. The driver monitoring system can include, but is not limited to, interior cameras for monitoring the operator's eye gaze and/or head orientation to indicate if the driver is attentive and/or awake.
However, since during autonomous travel of the road vehicle the driver is no longer responsible for driving, it is difficult if not impossible to ensure that the driver is always capable of taking over the driving task. In a worst case scenario, the driver may be e.g. distracted with other tasks or even asleep.
Thus there is a need for an improved solution to safely handle a situation where an autonomous road vehicle must stop and a driver thereof is not capable of taking over control the road vehicle.